The development of thin, compact and highly automated cameras as described, for instance, in U.S. Pat. Nos. 3,750,551; 3,744,385; 3,731,608; and 3,714,879 has been seen to have generated a concomitant need for a flat and compact battery source of power capable of operating a variety of electrical control instrumentalities having somewhat specialized power requirements. For instance, the battery must have a relatively high current output capacity for powering a motor driven film processing and reflex optics cocking assembly as well as electrically automated shutters incorporating electromagnetic drive devices and the like. Inasmuch as these instrumentalities are regulated by logic circuitry, requisite voltage levels must be sustained by the batteries during the noted current drains. A flat multicellular pile structure is particularly suited for providing a requisite low internal impedance battery. As described in U.S. Pat. No. 3,543,662, preferably, the thin battery is mounted within a film cassette assemblage and takes the shape of one film unit thereof. In consequence of this combined battery power supply-film supply arrangement, the compactness and thinness of a resultant foldable camera may be optimized.
For practical utilization in combination with a photographic film product, for instance, to form the composite cassette assembly described above, the thin batteries must not only be amenable to economic high volume production techniques, but also must exhibit a very high reliability. Such reliability is mandatory inasmuch as the batteries are packaged as an integral part of the film cassette assemblage and any dysfunctions on the part of the battery component thereof well may result in the wasting of the entire film cassette or pack.
To achieve requisite low unit costs in producing such thin batteries, the industry heretofore has looked to techniques wherein wide, continuous and multizoned webs of the sheet type components of the batteries or piles are manipulated along a production line to simultaneously form a plurality of cells and composites thereof. Following final formation of the electrochemically active multicell structures, the wide web formations thereof are slit and sheared as a later or last step in fabrication to form discrete battery units. These discrete units then are packaged as a component of film cassette assemblages whereupon they are forwarded to retail distribution channels.
When such multi-zone, wide web type high volume production battery assembly techniques are utilized, it is necessary that electrically conductive web type components of the battery pile structures serve as web carriers within the assembly system. For instance, electrically conductive materials preferably are utilized as electrode supports and as intercell connectors. When employed within a multi-zone wide web production scheme, these web-type conductive materials necessarily are combined with electrochemically active materials, and consequently, voltage build-up phenomena along the production line. Such electrochemical activity may have the effect of derogating from battery performance. Further, the battery structures necessarily evolved from this form of wide web assembly require a shearing of superposed conductive-insulative layers to evolve discrete battery structures. Utilization of such shearing procedures in forming discrete ones of the laminate battery structures may lead to product rejection due to edge shorting occasioned between contiguous electrically conductive layers.